On Wed, Apr 19, 2017 at 1:49 PM, Pavel Shub <pavel@xxxxxxxxxxxx> wrote: > On Wed, Apr 19, 2017 at 4:33 PM, Gregory Farnum <gfarnum@xxxxxxxxxx> wrote: >> On Wed, Apr 19, 2017 at 1:26 PM, Pavel Shub <pavel@xxxxxxxxxxxx> wrote: >>> Hey All, >>> >>> I'm running a test of bluestore in a small VM and seeing 2x overhead >>> for each object in cephfs. Here's the output of df detail >>> https://gist.github.com/pavel-citymaps/868a7c4b1c43cea9ab86cdf2e79198ee >>> >>> This is on a VM with all daemons & 20gb disk, all pools are of size 1. >>> Is this the expected amount of overhead per object? Is there anyway to >>> tweak bluestore settings? >> >> You're going to need to be clearer about what you mean by 2x overhead. >> Bluestore itself has a minimum size beneath which it will journal >> objects and then copy them into place, which might be considered 2x >> overhead. If you're talking about total number of cluster-wide disk >> ops, there's also a CephFS log which journals metadata updates that >> get flushed out to backing objects later, which might be considered 2x >> overhead. But I don't know what you mean just based on a ceph df. :) >> -Greg > > Sorry, I meant the disk space taken up by the files. I have a dataset > with lots of small files, my sample set 2.5gb in total size and 5gb on > a filesystem with a 4kb block size. When put the files inside ceph > bluestore they take up 6gb. Does bluestore have an internal block > size? Is there a way to adjust it? For comparison I created a > filestore OSD with 2kb block size and the data took up only 4.5gb. I can't speak with authority on bluestore, but at those total sizes I think you're just seeing the effects of the internal journaling. _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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